Providing a little more context to your question would have been preferable. I'm assuming the first three fields are: month day hours:minutes:seconds. I'll leave you to extrapolate from there.

Perl has different operators for string and numerical comparisons. '==' is the numerical equality operator; 'eq' is for strings. See perlop for all the different operators; perlop - Equality Operators specifically discusses '==' and 'eq'.

How you go about breaking up your line for comparison will depend on how much detail you want (e.g. do you want to look at 'yy:yy:yy' as a whole or are you interested in the subfields). I see two main options you might pursue: using the split function or using a regular expression.

The problem with this level of simplicity is when further down your code you hit $fields[7] and have to backtrack to determine which field index 7 refers to. Ways around this include giving symbolic names to the indices or capturing each field into a meaningfully named variable: